Solar cells are photovoltaic components for direct generation of electrical current from sunlight. Due to the growing demand for clean sources of energy, the manufacture of solar cells has expanded dramatically in recent years and continues to expand. Transparent conductive oxide, TCO, films are commonly used in solar cells due to their versatility as transparent coatings and also as electrodes. As such, the TCO films have a high transmittance and a low resistivity to serve their multiple purposes. Previous methods and techniques for attempting to optimize both transmittance and resistivity without introducing contamination or incurring severe cost increases, have not been wholly successful. In many cases, reducing resistance by adding dopants causes an undesirable decrease in transmittance.
One approach is to provide a metallic grid on the surface of the solar cell to decrease resistivity, but this comes at the expense of transmittance because the metal used in such grids is not transparent. The lower transmittance decreases the amount of electricity generated from sunlight, which is directly proportional to the solar cell area available for sunlight absorption. The dopants that have been tried as additives to the TCO to decrease resistance typically degrade the transmittance of the TCO especially in the long wavelength region.
Other attempts to optimize the TCO film effectiveness, i.e. minimizing resistance while maximizing transmittance, have also not been fully successful.
There is therefore a need in the art that addresses the conventional shortcomings and limitations of present methods and techniques and provides transparent conductive oxide films with suitably low resistance and high transmittance.